Fifty patients, aged 30-50 years, have been recruited (Octover 15, 1979) for the trial. The patients initially exhibited signs of gingivitis and advanced destructive periodontitis. On the average 50 percent or more of the supporting tissues was lost in each patient. They have been randomly distributed into three different main treatment groups (I, II, III). Following a baseline examination the phase of active treatment has been completed in most patients during this first year of the project. This means that 7 out of 10 patients are currently on chlorhexidine treatment (Group I), 22 patients out of 25 (Group IIa and III) are recalled for professional tooth cleaning once every two weeks, 10 patients are recalled for professional tooth cleaning once every four weeks (Group IIb) and 6 patients out of 10 (Group IIc) are recalled for professional tooth cleaning once every twelve weeks. The patients of Groups I and II have been treated with Widman flap procedure either with or without resection of bone (split mouth design). Ten patients (Group III) have been subjected to Widman surgery without resection of bone in two quadrants and to scaling in the two remaining quadrants (split mouth design). The data from the examinations two months and six months after surgery have been collected and are currently included in a computer program for analysis. GOAL FOR THE COMING YEAR: 5-10 additional patients will be incorporated in the trial to complete the groups. These individuals will be subjected to active treatment. All patients will be monitored at regular intervals and given preventive dental treatment in the manner described in the original research proposal, i.e. by the use of chlorhexidine mouth rinsings or by professional tooth cleaning carried out at various intervals.